LearningExpress Library - Provides practice tests, exercises, skill-building courses, e-books, and information you need to achieve the results you want. (Available via Discovery Texas. Call 214.509.4905 for login information.)
The College Board - Provides registration information for the SAT, as well as free practice questions with detailed explanations, sample essays, a full printable practice test with answers.
TExES / ExCET - Go to Preparation Materials on the left hand side of the page.